Halo 4 probably has the best campaign next to Halo 2 buutttt its not without its problems.
The best aspect of the campaign is the story. I'm really glad that they are diving into John's character more and bringing his emotionless attitude into play. The relationship between him and Cortana furthers this development and puts him into situations you've never seen him in before. Without giving anything away, I haven't heard John raise his voice since Combat Evolved in the beginning of The Two Betrayals. Cortana's descendent into madness is extremely tense. She is literally a ticking time bomb and the further you go into the campaign the more aggressive she gets. This adds great suspense and your curiosity grows as you keep playing.
The visuals are amazing. Halo 4 uses LA Noire's motion capture technology and perfects it. The expressions are incredibly detailed and the facial performances are outstanding. In speaking of performances I'm expecting many of the voice actors in the game including Steve Downes and especially Jen Taylor to be nominated for best vocal performance. The only small complaint I have with the presentation is the music placement. It comes up awkwardly and some of the best moments in the soundtrack don't even come in the game like the second half of Green and Blue which I was really looking forward to.
The gameplay is a lot more strategic. Veterans should not let their guard down when playing this. If you go rambo mode, you will get your ass kicked. Its imperative to plan your moves before going into play. It makes the gameplay experience less predictable. In speaking of predictable there is a major flaw in this game which is why I gave it a 9. The structure of the levels. There are too many flip switch objectives and they are pretty repetitive and just slows down the game but only a bit. I'm hoping in Halo 5 there will be less of that. This is made up by the vehicle sections however which are fast paced and challenging.
Overall even though there are some flaws, Halo 4 is a great game! Halo fans will not be disappointed!